A diffuse radiation which
consists of the cumulative infrared emission from all galaxies
throughout cosmic history. It is about 50 times weaker than the
→ cosmic microwave background radiation (CMBR).
Since the CIB is produced by the dust within such
galaxies, it carries a wealth of information about the processes of
star formation therein.

An orbiting infrared telescope (60 cm mirror) which successfully operated from launch
in January 1983 until the supply of coolant ran out in November 1983.
It was a collaborative mission between NASA, the Netherlands, and the UK, and mapped
95% of the whole sky in the wavelength bands 12, 25, 60, and 100 microns.

A European Space Agency satellite which carried the most sensitive infrared telescope
ever launched. It operated between November 1995 and April 1998 and
made particularly important observations of the dusty regions of the Universe.
ISO was equipped with four science instruments: an infrared camera (CAM), a
long-wavelength spectrometer (LWS), a photo-polarimeter (PHT), and a
short-wavelength spectrometer (SWS). The instruments jointly covered wavelengths
from 2.5 to around 240 microns with spatial resolutions
ranging from 1.5 arcseconds to 90 arcseconds. Its 60 cm diameter telescope was cooled by
superfluid liquid helium to temperatures of 2-4 K. The mission was a great technical,
operational and scientific success. During its routine operational phase, ISO
successfully made some 30,000 individual imaging, photometric,
spectroscopic, and polarimetric observations ranging from objects in
our own solar system to the most distant extragalactic sources.